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June 26, 2013 — Contrary to popular belief, crabgrass does not thrive in lawns, gardens and farm fields by simply crowding out other plants. A new study in ACS’ Journal of Agricultural and Food Chemistry has found that the much-despised weed actually produces its own herbicides that kill nearby plants.

Chui-Hua Kong and colleagues point out that crabgrass is not only a headache for lawns and home gardens, but also a major cause of crop loss on farms. Scientists long suspected, but had a hard time proving, that the weed thrived by allelopathy. From the Greek “allelo-,” meaning “other,” and “-pathy,” meaning “suffering,” allelopathy occurs when one plant restricts the growth of another by releasing toxins. They set out to determine if crabgrass has this oppressive ability.

Kong’s team isolated three chemicals from crabgrass that affect the microbial communities in nearby soil and did indeed inhibit the growth of staple crops wheat, corn and soybeans. “The chemical-specific changes in [the] soil microbial community generated a negative feedback on crop growth,” the scientists said, noting that the chemicals also would have a direct toxic effect on other plants.

The authors acknowledge funding from the National Natural Science Foundation of China.

The U.S. Environmental Protection Agency has approved the registration of Dow Chemical’s Enlist Duo herbicide, a new blend of 2,4-D and glyphosate.

The product is intended for use on Dow’s Enlist genetically engineered corn and soybeans, which were approved by the Department of Agriculture last month.

Dow stated in a press release that EPA’s decision means that the company can “bring to the market this necessary, innovative technology that is expected to deliver significant growth for Dow while at the same time addressing a critical global challenge.”

The combination of the two chemicals “will control and help prevent further development of herbicide-resistant weeds,” the company said.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to both proposals, arguing that its use on millions of acres of farm fields could negatively impact both environmental and human health. Members of Congress and prominent doctors, scientists and researchers also expressed their opposition.

2,4-D was a component of Agent Orange, which was produced by Dow and Monsanto and used as a defoliant in Vietnam, and glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

The opposition groups are particularly concerned about the health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease. There are also risks of learning disabilities, behavioral problems and chronic diseases in children.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.

Now that EPA has announced its approval of Enlist Duo, these groups are outraged.

“EPA has turned its back on those it purports to protect — the American people and our environment,” said Andrew Kimbrell, executive director for the Center for Food Safety. He added that his organization will “pursue all available legal options to stop the commercialization of these dangerous crops.”

Ronnie Cummins, international director of the Organic Consumers Association (OCA), argued that now it’s time for consumers to “shut down this treadmill of higher doses of increasingly toxic poisons.” OCA now plans to put more effort into its campaigns for mandatory GMO-labeling laws and for federal policies that promote organic agriculture.

Rep. Peter DeFazio (D-OR) said that,“EPA shunned its duties to protect the environment and safeguard public health by bowing to corporate interests instead of relying on science.”

The U.S. Environmental Protection Agency has approved the registration of Dow Chemical’s Enlist Duo herbicide, a new blend of 2,4-D and glyphosate.

The product is intended for use on Dow’s Enlist genetically engineered corn and soybeans, which were approved by the Department of Agriculture last month.

Dow stated in a press release that EPA’s decision means that the company can “bring to the market this necessary, innovative technology that is expected to deliver significant growth for Dow while at the same time addressing a critical global challenge.”

The combination of the two chemicals “will control and help prevent further development of herbicide-resistant weeds,” the company said.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to both proposals, arguing that its use on millions of acres of farm fields could negatively impact both environmental and human health. Members of Congress and prominent doctors, scientists and researchers also expressed their opposition.

2,4-D was a component of Agent Orange, which was produced by Dow and Monsanto and used as a defoliant in Vietnam, and glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

The opposition groups are particularly concerned about the health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease. There are also risks of learning disabilities, behavioral problems and chronic diseases in children.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.

Now that EPA has announced its approval of Enlist Duo, these groups are outraged.

“EPA has turned its back on those it purports to protect — the American people and our environment,” said Andrew Kimbrell, executive director for the Center for Food Safety. He added that his organization will “pursue all available legal options to stop the commercialization of these dangerous crops.”

Ronnie Cummins, international director of the Organic Consumers Association (OCA), argued that now it’s time for consumers to “shut down this treadmill of higher doses of increasingly toxic poisons.” OCA now plans to put more effort into its campaigns for mandatory GMO-labeling laws and for federal policies that promote organic agriculture.

Rep. Peter DeFazio (D-OR) said that,“EPA shunned its duties to protect the environment and safeguard public health by bowing to corporate interests instead of relying on science.”

The U.S. Environmental Protection Agency has approved the registration of Dow Chemical’s Enlist Duo herbicide, a new blend of 2,4-D and glyphosate.

The product is intended for use on Dow’s Enlist genetically engineered corn and soybeans, which were approved by the Department of Agriculture last month.

Dow stated in a press release that EPA’s decision means that the company can “bring to the market this necessary, innovative technology that is expected to deliver significant growth for Dow while at the same time addressing a critical global challenge.”

The combination of the two chemicals “will control and help prevent further development of herbicide-resistant weeds,” the company said.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to both proposals, arguing that its use on millions of acres of farm fields could negatively impact both environmental and human health. Members of Congress and prominent doctors, scientists and researchers also expressed their opposition.

2,4-D was a component of Agent Orange, which was produced by Dow and Monsanto and used as a defoliant in Vietnam, and glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

The opposition groups are particularly concerned about the health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease. There are also risks of learning disabilities, behavioral problems and chronic diseases in children.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.

Now that EPA has announced its approval of Enlist Duo, these groups are outraged.

“EPA has turned its back on those it purports to protect — the American people and our environment,” said Andrew Kimbrell, executive director for the Center for Food Safety. He added that his organization will “pursue all available legal options to stop the commercialization of these dangerous crops.”

Ronnie Cummins, international director of the Organic Consumers Association (OCA), argued that now it’s time for consumers to “shut down this treadmill of higher doses of increasingly toxic poisons.” OCA now plans to put more effort into its campaigns for mandatory GMO-labeling laws and for federal policies that promote organic agriculture.

Rep. Peter DeFazio (D-OR) said that,“EPA shunned its duties to protect the environment and safeguard public health by bowing to corporate interests instead of relying on science.”

Although the U.S. Environmental Protection Agency (EPA) said in April that it plans to permit a new weed killer called Enlist Duo onto the market, consumer advocates are attempting to dissuade the agency from doing so before a final decision is made.

The herbicide isa combination of 2,4-D and glyphosate and is made by Dow AgroSciences. If approved, it would be used on millions of acres of farm fields in combination with a new type of herbicide-resistant genetically engineered corn and soybean crops and at least triple the use of 2,4-D.

Glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

When announcing the agency’s inclination to approve Enlist Duo, EPA added that “the proposal would impose requirements on the manufacturer including robust monitoring and reporting to EPA, grower education and remediation and would allow EPA to take swift action to impose additional restrictions on the manufacturer and the use of the pesticide if resistance develops.”

EPA accepted public comments on the decision until June 30 and is expected to issue a final decision in late summer or early fall.

The U.S. Department of Agriculture, which must grant approval of the crops genetically engineered to tolerate Enlist Duo, said it was prepared to its grant approval in January. USDA’s comment period closed on March 11.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to the proposals, and the EPA docket received more than 25,000 comments in total.At the end of June, 35 scientists, medical professionals and researchers also wrote to EPA Administrator Gina McCarthy to urge the agency not to approve Enlist Duo.

On Wednesday, the Center for Food Safety and the Environmental Working Group hosted a briefing for congressional staffers to persuade members of Congress to pressure the two agencies to reject the proposals because of the potential negative impacts on the environment and human health.

Panelists at the event included Doug Gurian-Sherman, senior scientist at Center for Food Safety; John Wargo, professor of Environmental Health and Politics at Yale University; Dr. Philip Landrigan, dean for global health at Mount Sinai School of Medicine; Dr. Catherine Thomasson, executive director at Physicians for Social Responsibility, and Gary Hirshberg, co-founder of Stonyfield Farm and chairman of Just Label It.

The consumer advocates are concerned about the serious health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease.

When pregnant women are exposed to pesticides of all kinds, their child can sustain learning disabilities, behavioral problems and possibly chronic diseases.

Safety advocates are also concerned that 2,4-D and glyphosate have not been tested for combined toxicity. “We’re very concerned that this combination is going to cause not only additive effects, but multiplicative or synergistic effects,” Thomasson said.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.Hirshberg called the herbicide a “three- to five-year solution, at best” and compared it to the issue of antibiotics overuse contributing to drug resistance.

Rep. Chellie Pingree (D-ME), who spoke at the start of Wednesday’s briefing, said that the struggle over Enlist Duo ties into the fight for the labeling of genetically modified food. It’s not just about giving consumers the chance to know the source of their food, but to voice whether they want to support the system.

“It’s an issue that 90 percent of the American public thinks that we should move ahead with … but sometimes when I turn around and say to people, ‘So what’s the part that worries you most about it?,’ honestly a lot of people don’t understand the health risks or the concerns or what the implications of it are,” she said.

Pingree and Rep. Peter DeFazio (D-OR) are hoping that more members of Congress sign on to their letter to McCarthy and Agriculture Secretary Tom Vilsack urging them not to approve Enlist Duo and 2,4-D-resistant crops.

Although the U.S. Environmental Protection Agency (EPA) said in April that it plans to permit a new weed killer called Enlist Duo onto the market, consumer advocates are attempting to dissuade the agency from doing so before a final decision is made.

The herbicide isa combination of 2,4-D and glyphosate and is made by Dow AgroSciences. If approved, it would be used on millions of acres of farm fields in combination with a new type of herbicide-resistant genetically engineered corn and soybean crops and at least triple the use of 2,4-D.

Glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

When announcing the agency’s inclination to approve Enlist Duo, EPA added that “the proposal would impose requirements on the manufacturer including robust monitoring and reporting to EPA, grower education and remediation and would allow EPA to take swift action to impose additional restrictions on the manufacturer and the use of the pesticide if resistance develops.”

EPA accepted public comments on the decision until June 30 and is expected to issue a final decision in late summer or early fall.

The U.S. Department of Agriculture, which must grant approval of the crops genetically engineered to tolerate Enlist Duo, said it was prepared to its grant approval in January. USDA’s comment period closed on March 11.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to the proposals, and the EPA docket received more than 25,000 comments in total.At the end of June, 35 scientists, medical professionals and researchers also wrote to EPA Administrator Gina McCarthy to urge the agency not to approve Enlist Duo.

On Wednesday, the Center for Food Safety and the Environmental Working Group hosted a briefing for congressional staffers to persuade members of Congress to pressure the two agencies to reject the proposals because of the potential negative impacts on the environment and human health.

Panelists at the event included Doug Gurian-Sherman, senior scientist at Center for Food Safety; John Wargo, professor of Environmental Health and Politics at Yale University; Dr. Philip Landrigan, dean for global health at Mount Sinai School of Medicine; Dr. Catherine Thomasson, executive director at Physicians for Social Responsibility, and Gary Hirshberg, co-founder of Stonyfield Farm and chairman of Just Label It.

The consumer advocates are concerned about the serious health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease.

When pregnant women are exposed to pesticides of all kinds, their child can sustain learning disabilities, behavioral problems and possibly chronic diseases.

Safety advocates are also concerned that 2,4-D and glyphosate have not been tested for combined toxicity. “We’re very concerned that this combination is going to cause not only additive effects, but multiplicative or synergistic effects,” Thomasson said.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.Hirshberg called the herbicide a “three- to five-year solution, at best” and compared it to the issue of antibiotics overuse contributing to drug resistance.

Rep. Chellie Pingree (D-ME), who spoke at the start of Wednesday’s briefing, said that the struggle over Enlist Duo ties into the fight for the labeling of genetically modified food. It’s not just about giving consumers the chance to know the source of their food, but to voice whether they want to support the system.

“It’s an issue that 90 percent of the American public thinks that we should move ahead with … but sometimes when I turn around and say to people, ‘So what’s the part that worries you most about it?,’ honestly a lot of people don’t understand the health risks or the concerns or what the implications of it are,” she said.

Pingree and Rep. Peter DeFazio (D-OR) are hoping that more members of Congress sign on to their letter to McCarthy and Agriculture Secretary Tom Vilsack urging them not to approve Enlist Duo and 2,4-D-resistant crops.

Although the U.S. Environmental Protection Agency (EPA) said in April that it plans to permit a new weed killer called Enlist Duo onto the market, consumer advocates are attempting to dissuade the agency from doing so before a final decision is made.

The herbicide isa combination of 2,4-D and glyphosate and is made by Dow AgroSciences. If approved, it would be used on millions of acres of farm fields in combination with a new type of herbicide-resistant genetically engineered corn and soybean crops and at least triple the use of 2,4-D.

Glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

When announcing the agency’s inclination to approve Enlist Duo, EPA added that “the proposal would impose requirements on the manufacturer including robust monitoring and reporting to EPA, grower education and remediation and would allow EPA to take swift action to impose additional restrictions on the manufacturer and the use of the pesticide if resistance develops.”

EPA accepted public comments on the decision until June 30 and is expected to issue a final decision in late summer or early fall.

The U.S. Department of Agriculture, which must grant approval of the crops genetically engineered to tolerate Enlist Duo, said it was prepared to its grant approval in January. USDA’s comment period closed on March 11.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to the proposals, and the EPA docket received more than 25,000 comments in total.At the end of June, 35 scientists, medical professionals and researchers also wrote to EPA Administrator Gina McCarthy to urge the agency not to approve Enlist Duo.

On Wednesday, the Center for Food Safety and the Environmental Working Group hosted a briefing for congressional staffers to persuade members of Congress to pressure the two agencies to reject the proposals because of the potential negative impacts on the environment and human health.

Panelists at the event included Doug Gurian-Sherman, senior scientist at Center for Food Safety; John Wargo, professor of Environmental Health and Politics at Yale University; Dr. Philip Landrigan, dean for global health at Mount Sinai School of Medicine; Dr. Catherine Thomasson, executive director at Physicians for Social Responsibility, and Gary Hirshberg, co-founder of Stonyfield Farm and chairman of Just Label It.

The consumer advocates are concerned about the serious health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease.

When pregnant women are exposed to pesticides of all kinds, their child can sustain learning disabilities, behavioral problems and possibly chronic diseases.

Safety advocates are also concerned that 2,4-D and glyphosate have not been tested for combined toxicity. “We’re very concerned that this combination is going to cause not only additive effects, but multiplicative or synergistic effects,” Thomasson said.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.Hirshberg called the herbicide a “three- to five-year solution, at best” and compared it to the issue of antibiotics overuse contributing to drug resistance.

Rep. Chellie Pingree (D-ME), who spoke at the start of Wednesday’s briefing, said that the struggle over Enlist Duo ties into the fight for the labeling of genetically modified food. It’s not just about giving consumers the chance to know the source of their food, but to voice whether they want to support the system.

“It’s an issue that 90 percent of the American public thinks that we should move ahead with … but sometimes when I turn around and say to people, ‘So what’s the part that worries you most about it?,’ honestly a lot of people don’t understand the health risks or the concerns or what the implications of it are,” she said.

Pingree and Rep. Peter DeFazio (D-OR) are hoping that more members of Congress sign on to their letter to McCarthy and Agriculture Secretary Tom Vilsack urging them not to approve Enlist Duo and 2,4-D-resistant crops.

Although the U.S. Environmental Protection Agency (EPA) said in April that it plans to permit a new weed killer called Enlist Duo onto the market, consumer advocates are attempting to dissuade the agency from doing so before a final decision is made.

The herbicide isa combination of 2,4-D and glyphosate and is made by Dow AgroSciences. If approved, it would be used on millions of acres of farm fields in combination with a new type of herbicide-resistant genetically engineered corn and soybean crops and at least triple the use of 2,4-D.

Glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

When announcing the agency’s inclination to approve Enlist Duo, EPA added that “the proposal would impose requirements on the manufacturer including robust monitoring and reporting to EPA, grower education and remediation and would allow EPA to take swift action to impose additional restrictions on the manufacturer and the use of the pesticide if resistance develops.”

EPA accepted public comments on the decision until June 30 and is expected to issue a final decision in late summer or early fall.

The U.S. Department of Agriculture, which must grant approval of the crops genetically engineered to tolerate Enlist Duo, said it was prepared to its grant approval in January. USDA’s comment period closed on March 11.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to the proposals, and the EPA docket received more than 25,000 comments in total.At the end of June, 35 scientists, medical professionals and researchers also wrote to EPA Administrator Gina McCarthy to urge the agency not to approve Enlist Duo.

On Wednesday, the Center for Food Safety and the Environmental Working Group hosted a briefing for congressional staffers to persuade members of Congress to pressure the two agencies to reject the proposals because of the potential negative impacts on the environment and human health.

Panelists at the event included Doug Gurian-Sherman, senior scientist at Center for Food Safety; John Wargo, professor of Environmental Health and Politics at Yale University; Dr. Philip Landrigan, dean for global health at Mount Sinai School of Medicine; Dr. Catherine Thomasson, executive director at Physicians for Social Responsibility, and Gary Hirshberg, co-founder of Stonyfield Farm and chairman of Just Label It.

The consumer advocates are concerned about the serious health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease.

When pregnant women are exposed to pesticides of all kinds, their child can sustain learning disabilities, behavioral problems and possibly chronic diseases.

Safety advocates are also concerned that 2,4-D and glyphosate have not been tested for combined toxicity. “We’re very concerned that this combination is going to cause not only additive effects, but multiplicative or synergistic effects,” Thomasson said.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.Hirshberg called the herbicide a “three- to five-year solution, at best” and compared it to the issue of antibiotics overuse contributing to drug resistance.

Rep. Chellie Pingree (D-ME), who spoke at the start of Wednesday’s briefing, said that the struggle over Enlist Duo ties into the fight for the labeling of genetically modified food. It’s not just about giving consumers the chance to know the source of their food, but to voice whether they want to support the system.

“It’s an issue that 90 percent of the American public thinks that we should move ahead with … but sometimes when I turn around and say to people, ‘So what’s the part that worries you most about it?,’ honestly a lot of people don’t understand the health risks or the concerns or what the implications of it are,” she said.

Pingree and Rep. Peter DeFazio (D-OR) are hoping that more members of Congress sign on to their letter to McCarthy and Agriculture Secretary Tom Vilsack urging them not to approve Enlist Duo and 2,4-D-resistant crops.

Although the U.S. Environmental Protection Agency (EPA) said in April that it plans to permit a new weed killer called Enlist Duo onto the market, consumer advocates are attempting to dissuade the agency from doing so before a final decision is made.

The herbicide isa combination of 2,4-D and glyphosate and is made by Dow AgroSciences. If approved, it would be used on millions of acres of farm fields in combination with a new type of herbicide-resistant genetically engineered corn and soybean crops and at least triple the use of 2,4-D.

Glyphosate is the active ingredient in Roundup, the top-selling weed killer developed by Monsanto.

When announcing the agency’s inclination to approve Enlist Duo, EPA added that “the proposal would impose requirements on the manufacturer including robust monitoring and reporting to EPA, grower education and remediation and would allow EPA to take swift action to impose additional restrictions on the manufacturer and the use of the pesticide if resistance develops.”

EPA accepted public comments on the decision until June 30 and is expected to issue a final decision in late summer or early fall.

The U.S. Department of Agriculture, which must grant approval of the crops genetically engineered to tolerate Enlist Duo, said it was prepared to its grant approval in January. USDA’s comment period closed on March 11.

A number of farm, food, health, public interest, consumer, fisheries and environmental organizations submitted comments in opposition to the proposals, and the EPA docket received more than 25,000 comments in total.At the end of June, 35 scientists, medical professionals and researchers also wrote to EPA Administrator Gina McCarthy to urge the agency not to approve Enlist Duo.

On Wednesday, the Center for Food Safety and the Environmental Working Group hosted a briefing for congressional staffers to persuade members of Congress to pressure the two agencies to reject the proposals because of the potential negative impacts on the environment and human health.

Panelists at the event included Doug Gurian-Sherman, senior scientist at Center for Food Safety; John Wargo, professor of Environmental Health and Politics at Yale University; Dr. Philip Landrigan, dean for global health at Mount Sinai School of Medicine; Dr. Catherine Thomasson, executive director at Physicians for Social Responsibility, and Gary Hirshberg, co-founder of Stonyfield Farm and chairman of Just Label It.

The consumer advocates are concerned about the serious health risks associated with 2,4-D exposure, including non-Hodgkin lymphoma, suppressed immune function, lower sperm count, and a greater risk of Parkinson’s disease.

When pregnant women are exposed to pesticides of all kinds, their child can sustain learning disabilities, behavioral problems and possibly chronic diseases.

Safety advocates are also concerned that 2,4-D and glyphosate have not been tested for combined toxicity. “We’re very concerned that this combination is going to cause not only additive effects, but multiplicative or synergistic effects,” Thomasson said.

In terms of environmental effects, critics say that Enlist Duo will increase soils, surface and groundwater contamination and perpetuate the “pesticide treadmill,” which is when farmers use larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds, eventually requiring the use of different chemicals.Hirshberg called the herbicide a “three- to five-year solution, at best” and compared it to the issue of antibiotics overuse contributing to drug resistance.

Rep. Chellie Pingree (D-ME), who spoke at the start of Wednesday’s briefing, said that the struggle over Enlist Duo ties into the fight for the labeling of genetically modified food. It’s not just about giving consumers the chance to know the source of their food, but to voice whether they want to support the system.

“It’s an issue that 90 percent of the American public thinks that we should move ahead with … but sometimes when I turn around and say to people, ‘So what’s the part that worries you most about it?,’ honestly a lot of people don’t understand the health risks or the concerns or what the implications of it are,” she said.

Pingree and Rep. Peter DeFazio (D-OR) are hoping that more members of Congress sign on to their letter to McCarthy and Agriculture Secretary Tom Vilsack urging them not to approve Enlist Duo and 2,4-D-resistant crops.

Sep. 23, 2013 — Rice containing an overactive gene that makes it resistant to a common herbicide can pass that genetic trait to weedy rice, prompting powerful growth even without a weed-killer to trigger the modification benefit, new research shows.

Previously, scientists have found that when a genetically modified trait passes from a crop plant to a closely related weed, the weed gains the crop’s engineered benefit – resistance to pests, for example – only in the presence of the offending insects.

This new study is a surprising example of gene flow from crops to weeds that makes weeds more vigorous even without an environmental trigger, researchers say.

The suspected reason: This modification method enhances a plant’s own growth control mechanism, essentially making it grow faster – an attractive trait in crops but a recipe for potential problems with weedy relatives that could out-compete the crop.

“Our next question is whether this method of enhancing plant growth could be developed for any crop. We want to know whether growers could get higher yields in the crop and then, if it happened to cross with a related weed, whether it might make the weed more prolific as well,” said Allison Snow, professor of evolution, ecology and organismal biology at The Ohio State University and a lead author of the paper.

“It’s unusual for any transgene to have such a positive effect on a wild relative and even more so for herbicide resistance,” she said. “But we think we know why: It’s probably because the pathway regulated by this gene is so important to the plant.”

The work is the result of Snow’s longtime collaboration with senior author Bao-Rong Lu, a professor at Fudan University in Shanghai. Their publication appears online in the journal New Phytologist.

The weed-killer glyphosate, sold under the brand name Roundup, kills plants by inhibiting a growth-related pathway activated by the epsps gene. Biotech companies have inserted mutated forms of a similar gene from microbes into crop plants, producing “Roundup Ready” corn and soybeans that remain undamaged by widespread herbicide application.

But in this study, the researchers used a different method, boosting activation of the native epsps gene in rice plants – a process called overexpressing – to give the plants enough strength to survive an application of herbicide. Because companies that genetically modify commercial crops don’t fully disclose their methods, Snow and her colleagues aren’t sure how prevalent this method might be, now or in the future.

“This is a relatively new way to get a trait into a crop: taking the plant’s own gene and ramping it up,” Snow said. “We don’t know yet if our findings are going to be generalizable, but if they are, it’s definitely going to be important.”

To overexpress the native gene in rice, the scientists attached a promoter to it, giving the plant an extra copy of its own gene and ensuring that the gene is activated at all times.

The researchers conducted tests in rice and four strains of a relative of the same species, weedy rice, a noxious plant that infests rice fields around the world. By crossing genetically altered herbicide-resistant rice with weedy rice to mimic what happens naturally in the field, the researchers created crop-weed hybrids that grew larger and produced more offspring than unaltered counterparts – even without any herbicide present.

In regulated field experiments, the hybrids containing the overexpressed gene produced 48 percent to 125 percent more seeds per plant than did hybrid plants with no modified genes. They also had higher concentrations of a key amino acid, greater photosynthetic rates and better fledgling seed growth than controls – all presumed signs of better fitness in evolutionary terms.

“Fitness is a hard thing to measure, but you can conclude that if a gene gives you a lot more seeds per plant compared to controls, it’s likely to increase the plants’ fitness because those genes would be represented at a higher percentage in future generations,” Snow said.

When Snow and Lu set out to study this new genetic engineering method, they didn’t know what to expect.

“Our colleagues developed this novel transgenic trait in rice and we didn’t know if it would have a fitness benefit, or a cost, or be neutral,” Snow said. “With most types of herbicide resistant genes, there’s no benefit to a wild plant unless the herbicide is sprayed. A lot of transgenes in crop plants are either selectively neutral in wild plants or, if they have a benefit, it depends on environmental factors like insects, diseases or herbicides being present.”

Snow has a history in this area of research. She has found that genes from crop plants can persist in related weeds over many generations. In 2002, she led a study that was the first to show that a gene artificially inserted into crop plants to fend off pests could migrate to weeds in a natural environment and make the weeds stronger. She also has served on national panels that monitor and make recommendations about the release of genetically engineered species into the environment.

She is interested in identifying new possible outcomes of the growth of crop-weed hybrids that contain genetic modifications, but she doesn’t take sides about possible risks and benefits of genetically modified crops.

“It’s not always the end of the world if a weed starts to become a lot more common after acquiring a new trait – there may be effective ways to manage that weed,” Snow said. “You just can’t make sweeping generalizations about genetic engineering, and knowledge from ecological studies like ours can help inform risk assessment and biosafety oversight.”